Guys I am having some issues with my new bracket drag motor and I am looking for thoughts. ( maybe I am just being unrealistic )
The motor is a GM block 572 , filled with concrete with high dome pistons that produce 13.9 compression. It has 380 BB3 fully ccd heads and matching manifold. BLP 1520 carb build specifically for the combination. The camshaft is a custom grind comp cams, specs in the picture. Jesel rockers. and aeromotive vacuum pump. The headers are also a custom set that are 2 3/8 stepped to 2 1/2 primaries to a 5 inch collector.
I am using an areomotive 2000 electric fuel pump with -10 line from front to back.
The rear gear is a 5.14. and I am running an FTI 9 inch converter that flashes at 6200. I have the 2 -step set at 5600 rpm. The car is back -halved with a 4 link and kinetic double adjustable shocks on all corners. It weighs 3240 in race trim with me in it and believe the chassis is working very well.
So far the car has run a best of 5.70 at 120mph in the 1/8 with a 1.25 60 ft. ( 3.662 -330) I was shifting at 7200 on that pass at went through traps around 7000.
the problem I feel is the car does not seem to have a lot of power out of the gate. My 496 with oval port heads had a 60 ft of 1.24.
I know the 572 has put more weight on the nose than I had before but the 572 should be making a lot more horsepower and torq. than the 496 ever could.


Is it possible that the cam is too big or is opening too soon??? it seems like the power band is coming in higher than i can use it .

Things we have done:
Check all the ignition system ( 7al msd ,crank trigger, coil , wires , plugs)
Check fuel pump , regulator, car holds a steady psi down the track. tried running 8 psi and 9 psi no difference.
we have tried 2 other proven 9 stalls , one flashed 5500, one at 5800 , still no difference. Also tried chipping the 2 step from 4900 up to 5600.

also had 4 different carbs that have been dyno tested ranging from a 1050 SV1, a 1250 dominator , 1400 Jim evens and now the BLP. jetting all of them up or down and even going through the intermediate air bleeds in the BLP.
We have tried advancing the timing from 32- 38. it has improved with each combination of carb and stall at 36 degrees. falling off before and after 36. We have also tried many different shift points.
The best is at its current setup.
I plan on putting it on the dyno this winter but don't want to waste the money if I need to replace the cam first. if anyone is running a similar combo I would be interested on your thoughts.
Thanks ,
Chuck

 

I kinda feel like your headers are too big and the cam may have abit more duration than you need but shouldnt be considered too large. What you think its making? 840-850 hp? Not to shabby but depending how well ported the intake and heads are that may be considered a bit low for the setup. You can throw a wideband o2 on it and make a hit and see what air fuel is doing

do you run any collector extensions? Can you try extending it so total collector length is 17-18 inches or so. That should boost low end

 

The headers being too large is something that has always concerned me, but they where built to the specs that the engine builder recommended. the tubes are over 24 inches currently but there is not a lot of extension on it after the band exiting the fender well. that part is only 4.5 inches.
its something I will defiantly talk to the header builder about.
I believe we are running about 850 hp for the time slips with the weight of the car. I was thinking with this combo would be closer to 900-950. the heads and intake are fully ported from brodix but all I have are the advertised flow numbers which are stated at 440 cfm.
Could closing the intake a little earlier on a similar cam design help the torg curve come in a little sooner ?

 

Yeah id rather see a bit longer primary and maybe a 2.25-2.375 size with a 4” collector under car with 18” total length or so. Those you got now would love some nitrous

if there was a way to add a vband or slip fit extension to try on dyno that be quick and easy to test

also think the cam advance abit would pick up some down lower if it is installed at a 113. Going to a 109 would be a good test.

also could do a lash test on dyno. If you run it at .016 now hot, maybe open intake and exhaust up a few thousandths on both, and see if it helps. It should mimic less duration and delay events

 

Unfortunately without the front being tube chassis we were really limited on what could be done with the headers and with switching to a tall deck my ed quay headers would not fit anymore. I really liked how well those worked on my 496.
But those are all really sound ideas, its not looking good weather wise for getting her back to the track this year, but you never know. If not like you said I could definitely try them on the dyno this winter.
thank you
@Orr89RocZ
I will let you know what we find out , appreciate the help.

 

Your cam is very similar to mine in a 588. 4/7 swap. Yours has slightly more duration and roughly the same lift. Never checked the valve timing. For that size engine, it's more than enough. I run some very hogged out Dart 360 heads. Not sure the exact flow numbers but probably in the low 400 cfm range.

My engine however only uses Ed Quay 2-1/4 to 4" tubes/collectors. Your headers are huge. Maybe good for a comp eliminator car spinning the engine to 10,000 RPM

A Dyno tune is worth the money when you're trying to squeeze every last bit of performance out of an engine. Once you know where the powerband is, then you can select a converter to match the engine instead of guessing. You've already figured out where the best timing is. Changing jetting etc won't change where the engine wants it's timing so don't change that unless you do some major changes to the engine.

I race at altitude and my best 60' time is only 1.273. I only use a 1.76 powerglide and 4.86 gears on a 32" tire. If I switched to a 3 speed transmission, I could get a lower first gear and have more torque multiplication off the line but don't really need it. I already have enough torque to pull all 4 wheels off the ground with good track prep.

I run a custom build torque converter. Stalls around 6000. I shift at 7200 and the rpms fall back to 6200 after the shift. I go through the traps in the 7200-7400 rpm range but I only launch the car at 4500 because that's roughly where it makes peak torque.

I was never a fan of block filler unless you have an old thin walled production block. My Dart block is heavy enough as it is and has very thick cylinder walls so it don't need to be filled.

My best 1/8 time is 5.751 @ 120.61 so it's very similar to your setup.

 

I used to have those exact headers on the 496 i had, loved them, Ed Quay spent a lot of time and money to prefect them when they use those in NHRA..
Unfortunately I could not use them will the taller deck motor
. I have never used the concrete myself, it was already in the block when I bought it used.
I think you are correct though if i was spinning this combo at a much higher rpm I could probably take more advantage of the flow these headers are capable of.
Hopefully the guy who built them can come up with something to slow the flow, he is working on it.
its not his fault , he built them exactly to the specs i was given.
Hopefully we we learn something on the dyno that will help us improve the the torge in the lower power band.
By the way I believe i have mentioned this before, but i learned a lot of tricks from your post of your car when i first joined this forum. thanks for sharing. And thank you for the input Alky.

 

What is your bore and stroke?

 

 

 

Well you must have learned something because your car is still very fast even if you don't like the 60' time.

It still all boils down to power and weight. A race weight of 3200 pounds won't move off the line as fast as a 2800 pound vehicle with the same power. If I really wanted to go faster, I'd get rid of the body and put my powertrain into an altered.

 

Thank you Alky.
We have had a lot of fun with this car and won a few events in the process. You know how it goes we are always trying to make them better. It sounds like we are on the right track and you guys have given me some good ideas to try on the dyno to make sure we are getting everything out of it.
I think maybe my engine builder is a little high on his horsepower numbers, he is saying he gets around 1000 hp out of this combo in similar 540 builds, that could also be the cars are just faster because they are in a lighter car like you mentioned, Maybe I am setting the bar a little higher than it should be. It could also be the headers are just killing off the low end and I not spinning it high enough to take advantage of the higher power band.
We will keep plugging away on it.

 

It would seem if the heads are good with that valve size and cam i would expect it to turn abit more than 7200 rpm. Have you tried taking it higher?

 

I have not with the 1520 BLP. carb
With the 1400, 1250, and SV1 1050 carb the car slowed down trying to shift it higher than 7200.
Currently the car launches at 6200 ,shifts at 7200, falls back to 6500 after the shift, then goes through the traps about 7100 rpms.
the odd thing is it seems to hang around 6400 rpm after the initial hit, (sometimes it looks like it even falls to 6300) . i have had the go pro glued to the tach on a bunch of the passes and it does it every time.
that is why i have gone through the ignition and fuel system twice thinking either of them could be the cause for the that.
.

 

Only other thing is valve float

a 572 however can swallow up some cam.

playing with a cam program i have it would seem valve area limited you have a good bit more duration than needed. Its telling me valve size is good for a 6500-6600 rpm hp peak and power will hang on after that. Probably could drop 10 deg on both sides but idk if i trust the program much. Too many inputs that i dont fully understand lol.

 

My camshaft and internals are designed and capable of going to 8000 rpm but I don't spin the engine that high. I could go to 5.14 gears to allow more rpm but it's not worth it. 7200-7400 are more than enough.

 

Its interesting to see that information Orr89Rocz .
I have another buddy of mine who is also an engine builder and he has suggested using a cam that would close the intake faster feeling it would bring the torq up in the lower rpms.
he is suggesting a 281/294 111 =4.5
where the one installed now is a 285/300 113+ 4.5

His other suggestion was to make the heads flow more to take advantage of the cam that is currently in it , but that would come with about a $3000 price tag. lol

 

I agree Alky I have no intension of spinning my engine that high. I would however like to be able to optimize the power in the 6-7200 rpm range.

 

I was thinking something like that, 276-280 range on intake and def less exhaust duration than 300. Lsa can be similar 111-112 ish id say but intake centerline in more advanced. Be interesting to talk to some cam guys but id dyno first and loosen lash up few thousandths first to see how it responds

 

the $500 cam swap seems a lot more likely, than spending an extra 3 k on the heads to make them flow better, or having another custom set of headers made.

 

Yeah I understand that but id love to see a header test lol. At very least a dyno run some how putting extensions on collector to make it a total of 17-19” range

 

I would think we could at least do that. It would be interesting to see how the torq cure and hp would change with just adding extensions or even cones into the collectors. . The dyno guy said he has a couple sets of headers as well.

 

Just for another reference point. I have a 584 bbc I put together with 385 bmf heads 14.1 comp and a cam with the same duration figures as yours but on a wider lsa (114) and looser lash but more lift (.850 both). Stock suspension small tire class. 1.80 glide with 4,10 in back. 34 degrees and grid pulling some out on the hit. I built a 1250 on top along with ed's headers 2.25. I had merges put in the headers also. Motor wants rpm. I only ran it to 7600 shift for motor hits while I got it dialed in.

I set it up n20 a bit as I have a sledgehammer plate on top. But even off the gas when dialing in .70's was easy leaving at 3500 on the line along with a tight converter and laboring the motor and having the vacuum pump low (6 inches pulling). Bottle on is a different story ;-)

I like the header setup you have on there! Who made those? Would love to put a set on for myself since the nitrous would love them.

 

That sounds like a nice combo izcain. Here is the contact info for Jim Hallowell on the headers. He is currently working out of Xtreme Muscle cars in Illinois. the shop number is 618- 644-4185
here are some better images of the headers. As you can guess they where not cheap , I believe Jim said he had about 30 hours in them.

 

I'm not sure I even want to know the price. Probably a minimum of $2000

With so little room under the car for large tube headers, this is the way to go especially for a drag car. Street car however would need some sort of mufflers. Although they do make short fender exit mufflers, I doubt they would be quiet enough for street use.

 

They where around $2500 out the door with the bands and extensions. I had them priced at a couple other shops and that was a deal, not to mention he had them done in a week, which was not an easy task considering the material shortage. Mild tube would have been less expensive but once I was in that deep, why go cheap.
As you guys know without the car being tube chassis there are not a lot of options for these cars. With it being a tall deck block it even left me with fewer choices.
I definitely wanted to get the menthol fumes out from under the car.

I still believe the ed quay headers are the best you can buy ( performance wise) for an off the shelf header for a big block swap in these cars.

They are loud Alky, I do notice a lot more people covering their ears when I do a burnout, the funny thing is it extremely quiet in the car for me.

 

At least with my long tube Ed Quay headers, I have two 90* elbows coming off each of the collectors to be able to run mufflers under the door sills. The extra exhaust however does add 45 pounds to the car. I've had a lot of comments on how well the car sounds going down the track when running mufflers.

I agree that off the shelf headers are not the way to go. Every car seems to be a little big different. Because of how I have the engine positioned in the car, one of the header tubes on the passenger side has a huge dimple hammered into it to clear suspension. Doesn't affect performance at all. There's a good youtube video showing modified header tubes like what I've done while on a dyno and there is no performance loss.

 

We finally got a chance to the run the motor on a dyno. Unfortunately we did not have the time or money to run back to back pulls on the cam swap, so the pulls where done on the new cam only. It wound up installed straight up, after it was degreed in.

it made 970 hp at 7200 rpm which is right in the powerband we are looking to run it.

it did not start out making anywhere close to that.
.We made a 15 hp gain right off the bat when we noticed the vacuum pump was not pulling any vacuum, after pulling it apart and cleaning it we had it back to working order.
after adding timing and fuel we found gains of another 25 hp. After being satisfied that we had that right, (which believe it or not, 33 degrees was what it liked the best,)we then decided to add a 2 inch open spacer with was good for another 20.

after we where confident we had everything we could find we started swapping headers and unfortunately mine dropped the horsepower by 20 hp.
a similar dyno tech header made the best pulls and after examining them side to side we notice that mine choke down to only a 3.5 diameter passage where the collector meets and then expands outward to 5 inches. Where the dyno tech was 4.5 all the way to the end. So I will be talking to my header guy to see if we can correct that.
The smaller diameter headers we tried killed almost
twice that much. So I do not believe that the tubes are too big as was earlier speculated.

over all I am extremely happy with the power the little GM truck block is making. Now we will see if we can translate some of those new found ponies to the pavement. 😎

 

If you're interested, fill in the blanks and I'll run it through PipeMax.
It's an older version but should have some relevance for you.

 

Nice results. Cam seems to have helped. Did you pulll it any lower than 6300? Lots of trq in the 5000-6000 range i bet. Maybe doesnt need quite that much stall speed?

surprised on the headers. What size was the smallest set and what collector was on it?

how long was the collector on the dynatech ones that made best power? Were any extensions added?

3.5” choke seems tight but your collector length is also pretty short once it gets to 5”. Thats probably killing it, less choke, less angle on convergence and touch more length should make more, atleast under the curve

 

Further to the header debate I've filled in the blanks as best I could. Should be close.
Except maybe for the VE.

 

Yes at the beginning we made pulls starting as low as 5500 RPMs , it made peak torq at 5900
It was 775. The curve is actually very steady as you can see. Not sure it worth sending the converter back to have a couple 100s taken out at this point.
but we will see how it acts once it’s at the track.

We all agree the lobe separation definitely brought the powerband down into a more useable place for what we are trying to do.

the dyno tech heads where the exact length as mine,
the only difference was the tapper at the collector.

 

That is impressive information Skinny.
I will have the dyno guy measure his set and get back to you on the exact collector length.

after reading what I wrote earlier I probably need to clarify. The dyno tech and mine where the same length over all with the same steps on the down tubes. The collector was easily twice the length of my collector, and it stayed a consistent 4.5
from end of the down tubes through where they merged all the way to the end.
I would have really like to at least add more to mine during the test like you suggested but we just weren’t
able to come up with the extra 5 inch pipe to get it done.
He didn’t even know what brand the smaller set was
but it was a 2inch non stepped header with a 3.5 inch diameter collector, I do not know what the collector length was, and to be fair we only made one pull and did not even try different jets or timing with them.
it was just getting too late.

 

You know as I do that's it's only simulation but it gives a perspective on what you have and what the virtual world says works.
What I find is that if something isn't working to my liking, often an analysis will bring that "aha!" moment.
For me personally, I'll use my results as a starting point. Then track days (it's been forever) will determine what's best.
Seems for a lot of racers, the collector length is a neglected tuning tool.

 

I feel like 2.25 would have been a good compromise, maybe even like pipemax says 2.25 step 2.375 into atleast 4” collector. 3.5 would have been too small imo. 4” likely ok but as you noticed 4.5” could do well. Just seems like an odd size. I kinda feel like 4-4.5 of the right length would have really shown some gains. Usually guess at the length per pipe max, and with a longer extension piece, do a pull and cut an inch or inch and a half off at a time and see what it does. I know its time consuming. With front exit you got you can do it easily on chassis dyno lol. It doesnt have to look pretty just get an idea of length

atleast you got an idea of the powerband and know to shift it higher like 7500-7600 now

 

Well guys, what's the saying " how fast you want to go is directly related to how much money you have to spend.
To change the collector out at this point is going to be about $1000.00 , $300 labor the rest in parts.
I cant see spending that at this time for 20 hp on a bracket car. I believe the money would be better spent somewhere else on the car.
Thanks again for all the help, and I will let you guys know how it compares to the slips from last year when we get a chance to run it this summer.

 

Thats the way it goes lol spend 1000$ on a small plate kit and hit with 250 lol

 

So I took the $1000 needed to fix the headers and decided to put it towards a better front end. After doing a lot of research i decided to go with a chrome molly racecraft K member, A-arms, and spindles, with rack and pinon. it was very easy to install, and i lucked out by being able to use my existing Willwood brakes. With removing the old parts including the old steering box I am hoping to shave off 100 pounds. I let you guys know when i get it on the scales. If nothing else i am sure its going to steer a lot better, the old stuff was pretty wore out.

 

I kinda wanna do the same, go to a rack and remove power steering and hydroboost but i love power steering and the brake feel lol. But i gotta cut weight out of my car

 

It will be interesting to see how much weight it will actually cut out. I had a manual box on mine already so probably not much of a change feel wise. It would be a lot tougher call to lose power steering over it.

 

Looking good Wolfster! My kit shows up tomorrow and I am super excited. Will post photos of the swap out once complete.
Appreciate all the help thus far! My car weighed 2475 lbs with stock K member and no engine or radiator.

 

I was able to get it on the scales and the Racecraft front end was worth 107 pounds of weight savings.
😎